If u have your lines off I would blow thru them with my air , and spray them out with carb cleaner, you do not want any particles of dirt or actually anything in the lines, so I would clean them extra good and make sure they a clear, replace with all new seal, make sure there is ref. oil in compressor, pump down and recharge system if your going back with r12 its expensive, but you can change it over to 134a, also I would definitly replace the dryer